private:
    const uint32_t M1 = 0x55555555; // 01010101010101010101010101010101
    const uint32_t M2 = 0x33333333; // 00110011001100110011001100110011
    const uint32_t M4 = 0x0f0f0f0f; // 00001111000011110000111100001111
    const uint32_t M8 = 0x00ff00ff; // 00000000111111110000000011111111

public:
    uint32_t reverseBits(uint32_t n) {
        n = ((n >> 1) & M1) | ((n & M1) << 1);
        n = ((n >> 2) & M2) | ((n & M2) << 2);
        n = ((n >> 4) & M4) | ((n & M4) << 4);
        n = ((n >> 8) & M8) | ((n & M8) << 8);
        return n >> 16 | n << 16;
    }

    uint32_t reverseBits1(uint32_t n) {
        uint32_t res = 0;
        for (int i = 0; i < 32; i++) {
            res = (res << 1) | (n & 1);
            n >>= 1;
        }
        return res;
    }